RFR: 8320131: Zero build fails on macOS after JDK-8254693

[Hao Sun]

The fix is trivial. We should include the standard C header `stdlib.h` [1], rather than non-standard one `malloc.h`.

[1] https://en.cppreference.com/w/c/memory/malloc

-------------

Commit messages:
 - 8320131: Zero build fails on macOS after JDK-8254693

Changes: https://git.openjdk.org/jdk/pull/16775/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=16775&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8320131
  Stats: 2 lines in 1 file changed: 1 ins; 1 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/16775.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/16775/head:pull/16775

PR: https://git.openjdk.org/jdk/pull/16775